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https://github.com/lm-sensors/lm-sensors.git
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Jean Delvare
38eb690928
git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@2369 7894878c-1315-0410-8ee3-d5d059ff63e0
77 lines
2.4 KiB
Plaintext
77 lines
2.4 KiB
Plaintext
Kernel driver `pca9540.o'
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=========================
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Status: Complete but untested
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Supported chips:
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* Philips PCA9540
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Prefix: `pca9540'
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Addresses scanned: I2C 0x70
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Datasheet: Publicly available at the Philips Semiconductors website
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http://www.semiconductors.philips.com/pip/PCA9540.html
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Authors: Jean Delvare <khali@linux-fr.org>
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Module Parameters
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-----------------
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* force: short array (min = 1, max = 48)
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List of adapter,address pairs to boldly assume to be present
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* force_pca9540: short array (min = 1, max = 48)
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List of adapter,address pairs which are unquestionably assumed to
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contain a `pca9540' chip
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* ignore: short array (min = 1, max = 48)
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List of adapter,address pairs not to scan
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* ignore_range: short array (min = 1, max = 48)
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List of adapter,start-addr,end-addr triples not to scan
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* probe: short array (min = 1, max = 48)
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List of adapter,address pairs to scan additionally
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* probe_range: short array (min = 1, max = 48)
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List of adapter,start-addr,end-addr triples to scan additionally
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Note that the force and force_pca9540 parameters are equivalent here.
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Description (from the Philips web site)
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---------------------------------------
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The PCA9540 is a 1-of-2 bi-directional translating multiplexer, controlled
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via the I2C bus. The SCL/SDA upstream pair fans out to two SCL/SDA downstream
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pairs, or channels. Only one SCL/SDA channel is selected at a time,
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determined by the contents of the programmable control register.
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Accessing the PCA9540
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---------------------
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The PCA9540 is almost impossible to detect. We are lucky that no other
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known chip lives at address 0x70.
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Beware that the PCA9540 has a single internal register. It does work with
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READ BYTE and WRITE BYTE commands, contrary to regular chips which use
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READ BYTE DATA and WRITE BYTE DATA. Using i2cdump on the PCA9540 will
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actually *write* to it and leave its internal register to value 0x07 (i.e.
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no downstream channel selected).
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/proc Interface
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---------------
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There is a single read/write file, named "channel".
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0 = no downstream channel selected
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1 = first downstream channel selected
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2 = second downstream channel selected
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Chip Features
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-------------
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Chip `pca9540'
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LABEL LABEL CLASS COMPUTE CLASS ACCESS MAGNITUDE
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channel NONE NONE RW 0
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LABEL FEATURE SYMBOL SYSCTL FILE:OFFSET
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channel SENSORS_PCA9540_CHANNEL channel:1
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